Influence of Fat Source and Xylanase Supplementation on Performance, Utilisation of Energy and Fat, and Caecal Microbiota Counts in Broiler Starters Fed Wheat-Based Diets

An experiment was conducted to determine the interaction between fat source and xylanase supplementation on the performance, utilisation of energy and fat, and caecal microbiota counts in broiler starters fed wheat-based diets. The experimental design was 2×2 factorial arrangement of treatments, which included two fat sources (60 g/kg soybean oil or tallow) and two levels of enzyme supplementation (without or with exogenous xylanase). Irrespective of the fat source, xylanase supplementation increased (P<0.01) the weight gain and lowered (P<0.01) the feed per gain. Birds fed diets with soybean oil diets had higher (P<0.001) weight gain, fat retention and fat digestibility, and lower feed per gain compared to those fed tallow supplemented diets. Feed intake was not affected (P>0.05) by dietary treatments. Xylanase addition improved (P<0.01) the apparent metabolisable energy in diets containing either fat source, but the effect was more pronounced in birds fed the diet containing tallow. The number of Lactobacillus spp. was lowered (P<0.05) by enzyme supplementation in birds fed tallow diets, but unaffected (P>0.05) in those fed soybeans oil diets. The number of Clostridium spp. was found to be higher (P<0.01) in birds fed enzymesupplemented diets. Overall, under the conditions of the present study, the addition of xylanase improved the growth and feed efficiency of broiler starters and the responses were not influenced by the fat source.